Spring reinforced extensible catheter

ABSTRACT

An extensible catheter comprising a flexible tubular housing with a circularly cylindrical passage extending therethrough. A flexible metallic helical spring having a plurality of identical turns fits in the passage in abutment with the wall. The innermost boundary of the turns forms an axial guideway for guiding a pair of heads, each disposed on a conduit section which projects beyond the tube. A retainer member makes a fluid-sealing structural fit at each end of the housing, holds the heads in the passage, and makes a sliding fluid-sealing fit with the outer wall of the respective conduit section. The relative axial lengths of the passage and of the heads are such as to permit the axial spacing apart of the heads and therefore the total length of the catheter to be varied.

[ 1 3,738,365 June 12, 1973 Primary Examiner-Dalton L. Truluck Att0rneyD. Gordon Angus and Donald D. Mon

[57] ABSTRACT An extensible catheter comprising a flexible tubularhousing with a circularly cylindrical passage extending therethrough. Aflexible metallic helical spring having a plurality of identical turnsfits in the passage in abut- CATHETER Inventor: Rudolf R. Schulte, 600Pine Avenue,

(loleta, Calif. 93017 Filed: Nov. 1, 1971 Appl. No.: 194,308

Related US. Application Data Continuation-impart of Ser. No. 843,517,July 22, 1969, Pat. No. 3,623,484.

United States Patent Schulte SPRING REINFORCED EXTENSIBLE 10 Claims, 3Drawing Figures 5 5 .km AA iii-E22: w

ment with the wall. The innermost boundary of the turns forms an axialguideway for guiding a pair of heads, each disposed on a conduit sectionwhich projects beyond the tube. A retainer member makes a fluidsealingstructural fit at each end of the housing, holds the heads in thepassage, and makes a sliding fluidsealing fit with the outer wall of therespective conduit section. The relative axial lengths of the passageand of th w I 0 XVfl R R f v -\\i\\ 0 5 o w c BBm w 5 5 m, a 7 79 %88 33 4 /ZZ S 4 21 0 81 n l 01 16R n" m n R u n nu o N m n 5 E u ""43 "Hun""3 d L n u n u D. u 8A a "l n n A n 82 "up t a i. m C e m m m Rm O r. W:n me B WIT l S t "N" "A e w T a mT wm m N m mmm SGFFRS G u H E C T I owmn n mm& 99999 H mm NHHHHH N/ I. .f. 7294 CGO U .l 1 d E Std R 56124 69028 5 UIF .m 62733 9 ll] .1 2 9 2 6 MMH% %6 6 PATENIEWZ 3.738.365

I 45 l I 47 INVENTOR. 41/000 R. 50/0475 5Y2 6 z i A TTO/Q/VfVS.

CROSS REFERENCE TO OTHER PATENT APPLICATION This patent application is acontinuation-in-part of applicants co-pending U.S. Pat. application,Ser. No. 843,517, filed July 22, 1969, now U.S. Pat. No. 3,623,484,entitled Physiological Shunt Systems.

This invention relates to catheters for use in drainage of fluids withinthe human body and in particular to a spring-reinforced catheter whosetotal length can adjustably be varied.

Adjustably varied catheters are known in the art, one example can befound in applicants parent U.S. Pat. No. 3,623,484 referred to aboveentitled Physiological Shunt Systems. It is an object of such a catheterto lengthen as its user grows, without requiring movement of its ends(which may be affixed to particular regions of the human body), orrequiring stretching'of the device, or requiring its removal andreplacement by a catheter of a different and more suitable length.

The aforesaid catheter performs well, but in practice its has been founddesirable to isolate the relatively sliding members from externalcompressive and kinking forces, and also to reduce surface-to-surfacecontacts of like substances such as silicone rubber which might have atendency to adhere to each other, and cause galling upon movement, orwhich might tend to become fixed. Accordingly, it is an object of thisinvention to provide an extensible catheter which is reinforced toresist external forces and kinking and which can provide for relativemovement principally between dissimilar substances thereby reducing thetendency of the device to stick or to gall.

An extensible catheter according to this invention comprises a flexibletubular housing which has an interior wall bounding a passage throughthe housing. The

passage has a central axis. A flexible metallic helical spring has aplurality of identical turns and a constant inner and outer diameter.The spring extends axially in the passage in abutment with the wall. Theinnermost boundary of said turns forms a guideway. A conduit section isinserted in each end of the passage and a head on each conduit sectionprojects laterally beyond the sections and makes a sliding engagementwith the guideway. There is a flow passage through each of the sectionsand its respective head.

A pair of retainer members each makes a fluidsealing structural joinderwith the housing adjacent to a respective end thereof, and projects awayfrom the housing. It has an inner peripheral surface which surrounds itsrespective conduit section so as to make a sliding fluid-sealing fitwith the other wall of the respective conduit section and retains thehead in the passage. The relative axial lengths of the passage and ofthe heads are such as to permit the axial spacing apart of the heads tobe varied. The heads slide in the guideway and make sliding contact onlywith the said spring.

According to a preferred but optional feature of this invention, theconduit sections, heads and the housing are made of silicone rubber.

According to still another preferred but optional feature of theinvention, the spring is indented into the interior wall of the housing.

The above and other features of this invention will be fully understoodfrom the following detailed description and the accompanying drawings inwhich:

FIG. 1 is a perspective view of a drainage system for hydrocephalusutilizing the present invention;

FIG. 2 is an axial cross-section taken at 22 in FIG. 1; and

FIG. 3 is a cross-section taken at 33 of FIG. 2.

FIG. 1 shows an infant 10 which is afflicted with hydrocephalus, whichis an ailment in which cerebrospinal fluid does not drain properly fromthe head, with consequent compressive pressure on the brain andenlargement pressure inside the skull.

The shunt system 11 is provided to drain away excess fluid, andordinarily utilizes a catheter 12 such as that shown in the applicantspresently co-pending patent application Ser. No. 47,657 filed June 19,1970, now U.S. Pat. No. 3,626,950, entitled Catheter With AugmentedDrainage Means, which is thrust into the region of the brain to bedrained and which drains to a combined check valve and pump 13 which maybe of the type generally shown in Schulte U.S. Pat. No. 3,111,125 issuedNov. 19, 1963 entitled Drainage Device.

A catheter 14 according to this invention is joined to the outlet ofpump 13 and will extend through various veins 15 to the heart 16 intowhich the fluid is discharged. The catheter includes a pair of conduitsections l7, 18 which are joined together by means yet to be described.

Conduit section 18 will customarily be provided at its end with slitvalves 19 of the type generally shown in Heyer U.S. Pat. No. 3,020,913issued Feb. 13, 1962, entitled Surgical Drain. Protuberances 20 may beformed on the outer wall of conduit section 18 so as to aid in fixingthe end at some desired location. The details of the slit valves andprotuberances form no part of the present invention.

The foregoing system receives excess fluid at catheter 12, passes itthrough the check valve and pump 13 catheter 14, and discharges into theheart. It is a feature of the ailment known as hydrocephalus that whileit af fects adults it is generally an ailment of children and thechildren of course will grow in stature. As can be appreciated from FIG.1, the length between the pump and the tip within the heart will changeas the child grows. Until the catheter shown in the aforesaid ShulteU.S. Pat. No. 3,623,484 was invented, it was common practice to removeand replace the catheter from time to time in order to accommodate thechild's growth. This of course is an undesirable procedure to repeat anymore often than necessary if at all, and it is therefore an object ofthis invention to avoid this situation by providing means whereby thedevice can elongate or extend as the child grows. It will also beunderstood that this device may be located in such a manner that changein length can occur on either or both sides of its central point andthat the method or place of installation as shown in FIG. 1 is notlimiting in any manner.

Catheter 14 is shown in full detail in FIG. 2. It has a housing 25 withan interior wall 26 which forms a tubular passage 27 extending from endto end of the housing. Within the housing there is disposed a flexiblemetallic helical spring 30 which has an inner diameter 31 and an outerdiameter 32. The spring has a plurality of turns 33, 34 which areequally spaced apart by spacing 35 (sometimes called the pitch of aspring). The inner and outer diameters of all the turns are equal andare defined by the outermost boundaries, of the spring wire. The springat its outermost diameter bears in abutment against wall 26 of thepassage. ln manufacturing the device, the tube may be softened withxylene and the spring inserted. Then as the xylene evaporates, the tubeshrinks upon the spring so as to indent the spring into the wall forminga wavy pattern in the wall of the tube. However, waves such as wave 36will not extend inwardly beyond the inner diameter for reasons yet to bedescribed. The spring terminates short of both of the ends of thehousing.

The conduit sections 17, 18 have respective heads 40, 41 on their endsinside the passage, the outer diameter of the heads is substantiallyequal to the inner diameter of the spring and the axial spacing 35 issmaller than the axial length 42 of the heads. The heads projectlaterally beyond the outer wall of the respective conduit section.Accordingly the turns, or rather the innermost boundary of the turns,comprise a guideway for the heads, and the relative dimensions are suchthat the heads cannot become trapped between the coils of adjacentturns.

Retainer members 45, 46 are closely fitted into the respective ends ofthe passage in abutment with the ends of the spring. The retainermembers may be cemented or otherwise joined to the housing to make acontinuous peripheral fluid-sealing joint such as joint 47 and 48.

Each retainer member has an inner peripheral surface 49, 50 respectivelywhich surrounds its respective conduit section and makes at two places asliding fluidsealing fit 51, S2, S3, 54. There is thereby formed asubstantially fluid tight arrangement. It will be noted that when theheads move axially in the housing, fluid can bypass them through thespacing between adjacent turns so that there is no pressure developed inthe fluid as while the heads are being moved which might cause leakageof the device.

Formation of the retainer member as shown provides grooves 55, 56 towhich sutures may be tied for fixation of the housing if desired.

The heads, conduit sections, and housing will be made of medical gradesilicone rubber. This material is flexible and permits substantialrelatively easy bending and compression which will be resisted by theflexible spring. The spring may be made from round stainless steel wireof approximately 0.010 inches diameter wound with an outer diameter ofapproximately 0.110 0.l 15 inches with a pitch spacing of approximatelyl/32 inches.

The indentation of the spring turns into the wall of the housing willnot be sufficient to cause the material of the wall of the housing toabut against the head. Therefore there is provided a closely-sizedguideway for the heads in which there is no sliding surface-tosurfacecontact between the heads and another silicone rubber surface whichmight tend to seize or to gall. Instead contact is between the rubberhead and the metal of which the spring is made. This causes only a lightdrag, and is not subject to adherence or galling. The spring protectsthe head from binding compressive forces.

The relatively smaller line contact between the conduit sections and theretainer members at the sealing fits 51-54 do not cause much drag, anddo form a sliding fluid-seal. Furthermore, the retainer members arepreferably made of a different material from that of the housing, onewhich will be inherently stiffer, such as cast nylon in order that itcannot be compressed against the wall of the conduit section so aspossibly to occlude or drag on it. Also, it is a different material thanthat of the conduit segment so there is no tendency to adhere or togall. The retainer members can conveniently be made of relatively stiffnylon so as to make a light interference fit on the order of perhaps afew thousands of an inch with the wall of the tubing. The stiff retainermember will provide good support for sutures which may be tightly tiedto the respective grooves.

There is provided by this invention an extensible catheter for drainageof fluids from the human body such as hydrocephalus fluids in which easeof sliding of the telescoping members is provided, in whichsurfaceto-surface contact of materials which may tend to adhere to oneanother or to gall one another, is eliminated, and in which the possibleeffect of external forces in limiting relative internal movement isreduced if not entirely eliminated.

This invention is not to be limited by the embodiment shown in thedrawings and described in the description, which is given by way ofillustration and not of limitation but only in accordance with the scopeof the appended claims.

I claim:

I. An extensible catheter for use in a physiological fluid shunt system,said catheter comprising: a flexible tubular housing; an interior wallbounding a passage through the housing, the passage having a centralaxis; a flexible metallic helical spring having a plurality of identicalturns and a constant inner and outer diameter, the said spring extendingaxially in the passage in abutment with said wall, the innermostboundary of said turns forming a guideway; a pair of conduit sectionsslidably mounted in apposition with one another within said passage, ahead on each conduit section laterally projecting beyond the sectionsand making a sliding engagement with the said guideway, there being aflow passage through each sections and its head; and a pair of retainermembers each making a fluid-sealing structural joinder with the housingadjacent to a respective end thereof, and projecting away from saidhousing, and having an inner peripheral surface which surrounds itsrespective conduit section so as to make a sliding, fluid-sealing fitwith the outer wall of the respective conduit section and to retain thehead in the passage, the relative axial lengths of the passage and oftheheads being such as to permit the axial spacing apart of the heads to bevaried, the heads sliding in the guideway and making sliding contactonly with the said spring.

2. A catheter according to claim 1 in which the spring is indented intothe interior wall of the housing.

3. A catheter according to claim 1 in which the conduit sections, headsand the housing are made of silicone rubber.

4. A catheter according toclaim 3 in which the spring is indented intothe interior wall of the housing.

5. A catheter according to claim 3 in which the retainer members aremade of nylon, and are stiffer than the housing. I

6. A catheter according to claim 5 in which the spring is indented intothe interior wall of the housing.

7. A catheter according to claim 1 in which the axial length of theheads is greater than the axial spacing of the turns of the springwhereby the heads cannot be trapped between adjacent turns.

10. A catheter according to claim 9 in which the retainer members aremade of nylon, and are stiffer than the housing.

1. An extensible catheter for use in a physiological fluid shunt system,said catheter comprising: a flexible tubular housing; an interior wallbounding a passage through the housing, the passage having a centralaxis; a flexible metallic helical spring having a plurality of identicalturns and a constant inner and outer diameter, the said spring extendingaxially in the passage in abutment with said wall, the innermostboundary of said turns forming a guideway; a pair of conduit sectionsslidably mounted in apposition with one another within said passage, ahead on each conduit section laterally projecting beyond the sectionsand making a sliding engagement with the said guideway, there being aflow passage through each sections and its head; and a pair of retainermembers each making a fluid-sealing structural joinder with the housingadjacent to a respective end thereof, and projecting away from saidhousing, and having an inner peripheral surface which surrounds itsrespective conduit section so as to make a sliding, fluid-sealing fitwith the outer wall of the respective conduit section and to retain thehead in the passage, the relative axial lengths of the passage and ofthe heads being such as to permit the axial spacing apart of the headsto be varied, the heads sliding in the guideway and making slidingcontact only with the said spring.
 2. A catheter according to claim 1 inwhich the spring is indented into the interior wall of the housing.
 3. Acatheter according to claim 1 in which the conduit sections, heads andthe housing are made of silicone rubber.
 4. A catheter according toclaim 3 in which the spring is indented into the interior wall of thehousing.
 5. A catheter according to claim 3 in which the retainermembers are made of nylon, and are stiffer than the housing.
 6. Acatheter according to claim 5 in which the spring is indented into theinterior wall of the housing.
 7. A catheter according to claim 1 inwhich the axial length of the heads is greater than the axial spacing ofthe turns of the spring whereby the heads cannot be trapped betweenadjacent turns.
 8. A catheter according to claim 7 in which the conduitsections, heads and the housing are made of silicone rubber.
 9. Acatheter according to claim 8 in which the spring is indented into theinterior wall of the housing.
 10. A catheter according to claim 9 inwhich the retainer members are made of nylon, and are stiffer than thehousing.